Further Experimental Studies of the Selective Action of Predators.


  • E. J. Popham B. Sc, Ph.D., A.R.C.S., F.Z.S.


(1) The Intensity of Selection is influenced by the population density of the types of prey and predators.

(2) When the types of prey are not in equal proportions, those insects present in the largest numbers are destroyed relatively faster than the others.

(3) While the Selective Action of Predators can be reduced, or even eliminated, it has not been found to act in any way that would result in the preservation of a harmful or neutral character.

(4) Selection on mottled backgrounds may be less intense than on an even background of the same colour., where the mottling is approximately the same size as the insects.

(5) Insects with one or both hind legs amputated are destroyed faster than normal insects.

(6) Both sexes of Sigara distincta (Hemiptera, Corixidse) are destroyed equally.

(7) Scardinius erythropkthalmus (Rudd) are able to distinguish between certain species of Sigara.

(8) Nymphs of Hydrarachna geographica (Water Mites) tend to parasitize most those Corixids which do not harmonize with their environment.

(9) Males of Sigara distincta tend to choose as a mate a female either the same colour as themselves or slightly lighter.